feat: Step1~Step14 面板单步按钮 EventBus 解耦 + Handler 补全（Step8~Step14）+ 旧上帝类删除

- 9 个面板（step1~step6/step8_ml_train/step8_qaa/step9_ml_predict/step10）单步执行按钮从 parent 链上溯改为 global_event_bus.publish('RequestRunSingleStep')

- PipelineExecutor 新增 _on_request_run_single_step 订阅

- 新增 Handler: step8_ml_train / step9_ml_predict / step10_qaa_inversion / step11_concentration / step12_kriging / step13_visualization / step14_report

- 删除旧 water_quality_inversion_pipeline_GUI.py（上帝类已肢解完毕）

src/gui/panels/step8_qaa_panel.py

@@ -109,7 +109,7 @@ class Step8QAAPanel(QWidget):
         # 独立运行按钮
         self.run_btn = QPushButton("执行 QAA 反演")
         self.run_btn.setStyleSheet(ModernStylesheet.get_button_stylesheet('success'))
-        self.run_btn.clicked.connect(self.run_step)
+        self.run_btn.clicked.connect(self._on_run_single_clicked)
         layout.addWidget(self.run_btn)
 
         layout.addStretch()
@@ -212,8 +212,23 @@ class Step8QAAPanel(QWidget):
         else:
             self.output_path.set_path("")
 
+    def _on_run_single_clicked(self):
+        """通过 EventBus 发布单步执行请求（解耦面板与 PipelineExecutor）。"""
+        from src.gui.core.event_bus import global_event_bus
+
+        spectrum_path = self.spectrum_csv_file.get_path()
+        if not spectrum_path:
+            QMessageBox.warning(self, "输入错误", "请选择光谱 CSV 文件！")
+            return
+
+        config = {'step8_qaa': self.get_config()}
+        global_event_bus.publish('RequestRunSingleStep', {
+            'step_name': 'step8_qaa',
+            'config': config,
+        })
+
     def run_step(self):
-        """独立运行 QAA 反演"""
+        """独立运行 QAA 反演（旧版 parent 链上溯方式，保留兼容）。"""
         spectrum_path = self.spectrum_csv_file.get_path()
         if not spectrum_path:
             QMessageBox.warning(self, "输入错误", "请选择光谱 CSV 文件！")